It is known to equip a weaving loom with heddle frames intended to be controlled in a vertical oscillatory movement thanks to an appropriate device, such as a heald system or a dobby. It is known to mount on these frames heddles each provided with an eye for passage of warp yarn of the loom. The assembly between the heddles and the hooking bars of the crossbeams of a heddle frame may take various forms, as indicated in CH-A-155094, EP-A-0302798, FR-A-2 214 770 and U.S. Pat. No. 2,461,497. In the latter document, it is provided that an anti-rotation bar distinct from the crossbeams of the frame traverses the heddles supported by the latter. U.S. Pat. No. 4,519,424 teaches introducing the ends of a heddle in openings provided in the upper and lower beam members of a frame. An anti-rotation devices of the heddles may be used. As for DE-A-15 35 847, it discloses various end geometries of heddles. In the known devices, the effort of traction exerted by the frame to drive the heddles transits via contact surfaces of small total area.
Taking into account the manufacturing tolerances of this equipment and their possible deformations under the effect of the loads and violent accelerations to which they are subjected, a functional clearance of the order of 3 mm is generally provided between crossbeams of the frames and the ends of the heddles. Whenever the movement of the frames is reversed, a shock is therefore produced between each heddle and the bars of the crossbeams on which it is hooked in the upper and lower part, this resulting in a premature beating and wear of their respective contact surfaces. Now, taking into account the usual operating conditions of weaving looms in a damp atmosphere, the heddles and bars must be made of stainless materials of which the hardness is limited, while the treatments for increasing this hardness are expensive. Furthermore, the width of the surfaces for contact and for transmission of traction effort between the crossbeams and the heddles cannot be increased in view of the width of division of the frames and the density of the heddles over the width of the loom. The known heddles and hooking parts of the crossbeams of the heddle frames thus tend to wear out rapidly and this results in an increase in the clearance and breakages of heddles. Preventive maintenance operations should therefore be regularly carried out, this leading to the weaving looms concerned being repeatedly immobilized.
It is a more particular object of the present invention to overcome these drawbacks by proposing a novel system for hooking the heddles on the crossbeams of the corresponding frames, which makes it possible to limit the wear induced by the vertical oscillatory movements of this equipment.